Salt deposits exist as part of many underground geologic structures. Salt deposits can have many geological forms including bedded salt, salt anticlines, and salt piercement structures (diapirs). A specific type of salt diapiric structure is the salt dome. Salt deposits, as utilized herein, include the various underground geologic structures of salt amenable to development of cavities for storage of materials.
There are several properties of salt deposits which make cavities constructed in salt ideal storage sites. First, they are readily accessible generally by drilling a well. Second, cavities or storage spaces can be created at a relatively low cost when compared to surface storage facilities. Third, the salt in salt deposits, unlike most other geological structures, is impermeable to underground flow of liquids, and thus provides a relatively safe media for development of isolated storage receptacles.
For many years storage cavities have been created in salt deposits. Typically, a storage cavity in salt is created by drilling a well into the salt deposit and leaching a cavity by circulating raw water into the salt deposit through the well. Generally, oil, gas and other petroleum products have been stored in these cavities. U.S. Pat. Nos. 3,665,716 and 3,236,053 disclose the storage of waste in salt cavities.
The present invention is the first method for sequentially creating, evacuating, using, sealing, and reentering multiple, isolated stacked storage cavities in salt created from a single well. Although any type of material can be stored in the multiple stacked storage cavities of the present invention, the multiple stacked storage cavities are particularly well suited for storing waste material. The present invention also is the first method for creating, excavating, using and sealing salt cavities.